Thanks Abe. In case it is helpful for some: those using AWS EC2 VM
instances with an Elastic IP address (i.e. a static IP address) can ask
Amazon to resolve a reverse DNS lookup on the Elastic IP address to one DNS
address that they have set to resolve to that IP address. They can do so by
filling out a form available at this link:

https://aws.amazon.com/blogs/aws/reverse-dns-for-ec2s-elastic-ip-addresses/

The actual form is available here:

https://aws-portal.amazon.com/gp/aws/html-forms-controller/contactus/ec2-email-limit-rdns-request

Google Cloud has something similar - you can request a PTR record. With
Google Cloud you get the reverse DNS done quicker - AWS could take several
hours or a day to get it done. This link has more information:

https://cloud.google.com/compute/docs/instances/create-ptr-record

This can solve the issue of using SASL with ZooKeeper with server names.

On Mon, Jan 8, 2018 at 7:00 PM, Abraham Fine <[EMAIL PROTECTED]> wrote: